Medical implant components may be used within a patient for replacement surgery such as hip replacement surgery or the like. Such medical implant components may include femoral head components and acetabular cup components. With such components, a ball portion of the femoral head component is adapted to mate with a bearing portion of the acetabular cup component.
To provide an acceptable mating condition, the ball portion may be coated with a coating material. Typically, such coating may be applied by a chemical vapor deposition (CVD) process or a physical vapor deposition (PVD) process. These coating processes may enable only a relatively thin coating to be applied. That is, the maximum thickness typically attainable by either of these processes is approximately 20 microns.
The use of a relatively thin coating (e.g., 20 microns or less) on a bearing surface of a medical implant component may result in a failure of the coating during actually use. As an example, consider the situation if a foreign material were to get into the joint between the ball portion of the femoral head component and the bearing portion of the acetabular cup component. During movement, the foreign material may rub against the coating on the ball portion. As a result, a scratch or crack in the coating may develop which may spread into a larger crack. Additionally, other scratches or cracks may also develop and grow into larger cracks. Eventually, such crack or cracks may result in particles of the coating material being removed from or flaking off from such coating material. As is to be appreciated, such particles or flakes of the coating material inside a patient are not desirable.
In addition to above, there may be a number of other disadvantages associated with merely the use of a CVD or a PVD process or technique to coat a bearing surface of a medical implant component. For example, heat treating may not be performed after such coating is applied. As a result, there may not be any diffusion or substantially no diffusion of the coating material into the substrate material. In other words, in such situation, there may be a distinct boundary between the coating and the substrate of the medical implant component.
Additionally, the above-described techniques may produce a bearing surface which does not have a relatively hard surface. As a result, to minimize wear, the material of the mating implant component may be a relatively soft material or may have a relatively low hardness value.
Furthermore, the above-described techniques may be usable only with relatively simple shapes.
As such, it would be advantageous to provide a technique for applying a coating to a bearing portion of a component, such as a medical implant component, which would enable such coating to be relatively thick and/or to have a relatively hard surface and/or to be inter-diffused with the material of the substrate so as to improve the wear performance of such component. It would also be advantageous to provide such technique which may be usable with components having non-simple geometries or shapes.